Vim can detect the type of file that is edited. This is done by checking the
file name and sometimes by inspecting the contents of the file for specific
text.

:filetype:filet
To enable file type detection, use this command in your vimrc:

:filetype on

Each time a new or existing file is edited, Vim will try to recognize the type
of the file and set the 'filetype' option. This will trigger the FileType
event, which can be used to set the syntax highlighting, set options, etc.

NOTE: Filetypes and 'compatible' don't work together well, since being Vi
compatible means options are global. Resetting 'compatible' is recommended,
if you didn't do that already.

Detail: The ":filetype on" command will load one of these files:
Amiga $VIMRUNTIME/filetype.vim
Mac $VIMRUNTIME:filetype.vim
MS-DOS $VIMRUNTIME\filetype.vim
RiscOS Vim:Filetype
Unix $VIMRUNTIME/filetype.vim
VMS $VIMRUNTIME/filetype.vim
This file is a Vim script that defines autocommands for the
BufNewFile and BufRead events. If the file type is not found by the
name, the file $VIMRUNTIME/scripts.vim is used to detect it from the
contents of the file.
When the GUI is running or will start soon, the menu.vim script is
also sourced. See 'go-M' about avoiding that.

To add your own file types, see new-filetype below. To search for help on a
filetype prepend "ft-" and optionally append "-syntax", "-indent" or
"-plugin". For example:

:help ft-vim-indent
:help ft-vim-syntax
:help ft-man-plugin

If the file type is not detected automatically, or it finds the wrong type,
you can either set the 'filetype' option manually, or add a modeline to your
file. Example, for an IDL file use the command:

If filetype detection was not switched on yet, it will be as well.
This actually loads the file "ftplugin.vim" in 'runtimepath'.
The result is that when a file is edited its plugin file is loaded (if there
is one for the detected filetype). filetype-plugin

If filetype detection was not switched on yet, it will be as well.
This actually loads the file "indent.vim" in 'runtimepath'.
The result is that when a file is edited its indent file is loaded (if there
is one for the detected filetype). indent-expression

The filetype detection is not switched off then. But if you do switch off
filetype detection, the indent files will not be loaded either.
This actually loads the file "indoff.vim" in 'runtimepath'.
This disables auto-indenting for files you will open. It will keep working in
already opened files. Reset 'autoindent', 'cindent', 'smartindent' and/or'indentexpr' to disable indenting in an opened file.

command detection plugin indent
:filetype on on unchanged unchanged
:filetype off off unchanged unchanged
:filetype plugin on on on unchanged
:filetype plugin off unchanged off unchanged
:filetype indent on on unchanged on
:filetype indent off unchanged unchanged off
:filetype plugin indent on on on on
:filetype plugin indent off unchanged off off

To see the current status, type:

:filetype

The output looks something like this:

filetype detection:ON plugin:ON indent:OFF

The file types are also used for syntax highlighting. If the ":syntax on"
command is used, the file type detection is installed too. There is no need
to do ":filetype on" after ":syntax on".

To disable one of the file types, add a line in your filetype file, seeremove-filetype.

Use this if you started with an empty file and typed text that makes it
possible to detect the file type. For example, when you entered this in a
shell script: "#!/bin/csh".
When filetype detection was off, it will be enabled first, like the "on"
argument was used.

filetype-overrule
When the same extension is used for two filetypes, Vim tries to guess what
kind of file it is. This doesn't always work. A number of global variables
can be used to overrule the filetype used for certain extensions:

filetype-ignore
To avoid that certain files are being inspected, the g:ft_ignore_pat variable
is used. The default value is set like this:

:let g:ft_ignore_pat = '\.\(Z\|gz\|bz2\|zip\|tgz\)$'

This means that the contents of compressed files are not inspected.

new-filetype
If a file type that you want to use is not detected yet, there are four ways
to add it. In any way, it's better not to modify the $VIMRUNTIME/filetype.vim
file. It will be overwritten when installing a new version of Vim.

A. If you want to overrule all default file type checks.
This works by writing one file for each filetype. The disadvantage is that
means there can be many files. The advantage is that you can simply drop
this file in the right directory to make it work.ftdetect
1. Create your user runtime directory. You would normally use the first
item of the 'runtimepath' option. Then create the directory "ftdetect"
inside it. Example for Unix:

:!mkdir ~/.vim
:!mkdir ~/.vim/ftdetect

2. Create a file that contains an autocommand to detect the file type.
Example:

au BufRead,BufNewFile *.mine set filetype=mine

Note that there is no "augroup" command, this has already been done
when sourcing your file. You could also use the pattern "*" and then
check the contents of the file to recognize it.
Write this file as "mine.vim" in the "ftdetect" directory in your user
runtime directory. For example, for Unix:

:w ~/.vim/ftdetect/mine.vim

3. To use the new filetype detection you must restart Vim.

The files in the "ftdetect" directory are used after all the default
checks, thus they can overrule a previously detected file type. But you
can also use :setfiletype to keep a previously detected filetype.

B. If you want to detect your file after the default file type checks.

This works like A above, but instead of setting 'filetype' unconditionally
use ":setfiletype". This will only set 'filetype' if no file type was
detected yet. Example:

au BufRead,BufNewFile *.txt setfiletype text

You can also use the already detected file type in your command. For
example, to use the file type "mypascal" when "pascal" has been detected:

au BufRead,BufNewFile * if &ft == 'pascal' | set ft=mypascal
| endif

C. If your file type can be detected by the file name.
1. Create your user runtime directory. You would normally use the first
item of the 'runtimepath' option. Example for Unix:

:!mkdir ~/.vim

2. Create a file that contains autocommands to detect the file type.
Example:

Write this file as "filetype.vim" in your user runtime directory. For
example, for Unix:

:w ~/.vim/filetype.vim

3. To use the new filetype detection you must restart Vim.

Your filetype.vim will be sourced before the default FileType autocommands
have been installed. Your autocommands will match first, and the
":setfiletype" command will make sure that no other autocommands will set'filetype' after this.new-filetype-scripts
D. If your filetype can only be detected by inspecting the contents of the
file.

1. Create your user runtime directory. You would normally use the first
item of the 'runtimepath' option. Example for Unix:

See $VIMRUNTIME/scripts.vim for more examples.
Write this file as "scripts.vim" in your user runtime directory. For
example, for Unix:

:w ~/.vim/scripts.vim

3. The detection will work right away, no need to restart Vim.

Your scripts.vim is loaded before the default checks for file types, which
means that your rules override the default rules in
$VIMRUNTIME/scripts.vim.

remove-filetype
If a file type is detected that is wrong for you, install a filetype.vim or
scripts.vim to catch it (see above). You can set 'filetype' to a non-existing
name to avoid that it will be set later anyway:

:set filetype=ignored

If you are setting up a system with many users, and you don't want each user
to add/remove the same filetypes, consider writing the filetype.vim and
scripts.vim files in a runtime directory that is used for everybody. Check
the 'runtimepath' for a directory to use. If there isn't one, set'runtimepath' in the system-vimrc. Be careful to keep the default
directories!

autocmd-osfiletypesNOTE: this code is currently disabled, as the RISC OS implementation was
removed. In the future this will use the 'filetype' option.

On operating systems which support storing a file type with the file, you can
specify that an autocommand should only be executed if the file is of a
certain type.

The actual type checking depends on which platform you are running Vim
on; see your system's documentation for details.

To use osfiletype checking in an autocommand you should put a list of types to
match in angle brackets in place of a pattern, like this:

:au BufRead *.html,<&faf;HTML> runtime! syntax/html.vim

This will match:

- Any file whose name ends in ".html"
- Any file whose type is "&faf" or "HTML", where the meaning of these types
depends on which version of Vim you are using.
Unknown types are considered NOT to match.

You can also specify a type and a pattern at the same time (in which case they
must both match):

:au BufRead <&fff>diff*

This will match files of type "&fff" whose names start with "diff".

plugin-details
The "plugin" directory can be in any of the directories in the 'runtimepath'
option. All of these directories will be searched for plugins and they are
all loaded. For example, if this command:

set runtimepath

produces this output:

runtimepath=/etc/vim,~/.vim,/usr/local/share/vim/vim60

then Vim will load all plugins in these directories and below:

/etc/vim/plugin/ ~/.vim/plugin/ /usr/local/share/vim/vim60/plugin/

Note that the last one is the value of $VIMRUNTIME which has been expanded.

Note that when using a plugin manager or packages many directories will be
added to 'runtimepath'. These plugins each require their own directory, don't
put them directly in ~/.vim/plugin.

What if it looks like your plugin is not being loaded? You can find out what
happens when Vim starts up by using the -V argument:

vim -V2

You will see a lot of messages, in between them is a remark about loading the
plugins. It starts with:

When loading filetype plugins has been enabled :filetype-plugin-on, options
will be set and mappings defined. These are all local to the buffer, they
will not be used for other files.

Defining mappings for a filetype may get in the way of the mappings you
define yourself. There are a few ways to avoid this:
1. Set the "maplocalleader" variable to the key sequence you want the mappings
to start with. Example:

:let maplocalleader = ","

All mappings will then start with a comma instead of the default, which
is a backslash. Also see <LocalLeader>.

2. Define your own mapping. Example:

:map ,p <Plug>MailQuote

You need to check the description of the plugin file below for the
functionality it offers and the string to map to.
You need to define your own mapping before the plugin is loaded (before
editing a file of that type). The plugin will then skip installing the
default mapping.no_mail_maps
3. Disable defining mappings for a specific filetype by setting a variable,
which contains the name of the filetype. For the "mail" filetype this
would be:

:let no_mail_maps = 1

no_plugin_maps
4. Disable defining mappings for all filetypes by setting a variable:

:let no_plugin_maps = 1

ftplugin-overrule
If a global filetype plugin does not do exactly what you want, there are three
ways to change this:

1. Add a few settings.
You must create a new filetype plugin in a directory early in'runtimepath'. For Unix, for example you could use this file:

vim ~/.vim/ftplugin/fortran.vim

You can set those settings and mappings that you would like to add. Note
that the global plugin will be loaded after this, it may overrule the
settings that you do here. If this is the case, you need to use one of the
following two methods.

2. Make a copy of the plugin and change it.
You must put the copy in a directory early in 'runtimepath'. For Unix, for
example, you could do this:

cp $VIMRUNTIME/ftplugin/fortran.vim ~/.vim/ftplugin/fortran.vim

Then you can edit the copied file to your liking. Since the b:did_ftplugin
variable will be set, the global plugin will not be loaded.
A disadvantage of this method is that when the distributed plugin gets
improved, you will have to copy and modify it again.

3. Overrule the settings after loading the global plugin.
You must create a new filetype plugin in a directory from the end of'runtimepath'. For Unix, for example, you could use this file:

vim ~/.vim/after/ftplugin/fortran.vim

In this file you can change just those settings that you want to change.

Commands:
NewChangelogEntry Adds a new Changelog entry in an intelligent fashion
(see below).

Local mappings:<Leader>o Starts a new Changelog entry in an equally intelligent
fashion (see below).

Global mappings:NOTE: The global mappings are accessed by sourcing the
ftplugin/changelog.vim file first, e.g. with

runtime ftplugin/changelog.vim

in your .vimrc.<Leader>o Switches to the ChangeLog buffer opened for the
current directory, or opens it in a new buffer if it
exists in the current directory. Then it does the
same as the local <Leader>o described above.

Variables:
g:changelog_timeformat Deprecated; use g:changelog_dateformat instead.
g:changelog_dateformat The date (and time) format used in ChangeLog entries.
The format accepted is the same as for thestrftime() function.
The default is "%Y-%m-%d" which is the standard format
for many ChangeLog layouts.
g:changelog_username The name and email address of the user.
The default is deduced from environment variables and
system files. It searches /etc/passwd for the comment
part of the current user, which informally contains
the real name of the user up to the first separating
comma. then it checks the $NAME environment variable
and finally runs whoami and hostname to build an
email address. The final form is

Full Name <user@host>

g:changelog_new_date_format
The format to use when creating a new date-entry.
The following table describes special tokens in the
string:
%% insert a single '%' character
%d insert the date from above
%u insert the user from above
%p insert result of b:changelog_entry_prefix
%c where to position cursor when done
The default is "%d %u\n\n\t* %p%c\n\n", which produces
something like (| is where cursor will be, unless at
the start of the line where it denotes the beginning
of the line)

|2003-01-14 Full Name <user@host>
|
| * prefix|

g:changelog_new_entry_format
The format used when creating a new entry.
The following table describes special tokens in the
string:
%p insert result of b:changelog_entry_prefix
%c where to position cursor when done
The default is "\t*%c", which produces something
similar to

| * prefix|

g:changelog_date_entry_search
The search pattern to use when searching for a
date-entry.
The same tokens that can be used for
g:changelog_new_date_format can be used here as well.
The default is '^\s*%d\_s*%u' which finds lines
matching the form

|2003-01-14 Full Name <user@host>

and some similar formats.

g:changelog_date_end_entry_search
The search pattern to use when searching for the end
of a date-entry.
The same tokens that can be used for
g:changelog_new_date_format can be used here as well.
The default is '^\s*$' which finds lines that contain
only whitespace or are completely empty.

b:changelog_name b:changelog_name
Name of the ChangeLog file to look for.
The default is 'ChangeLog'.

b:changelog_path
Path of the ChangeLog to use for the current buffer.
The default is empty, thus looking for a file namedb:changelog_name in the same directory as the
current buffer. If not found, the parent directory of
the current buffer is searched. This continues
recursively until a file is found or there are no more
parent directories to search.

b:changelog_entry_prefix
Name of a function to call to generate a prefix to a
new entry. This function takes no arguments and
should return a string containing the prefix.
Returning an empty prefix is fine.
The default generates the shortest path between the
ChangeLog's pathname and the current buffers pathname.
In the future, it will also be possible to use other
variable contexts for this variable, for example, g:.

The Changelog entries are inserted where they add the least amount of text.
After figuring out the current date and user, the file is searched for an
entry beginning with the current date and user and if found adds another item
under it. If not found, a new entry and item is prepended to the beginning of
the Changelog.

Options:'expandtab' is switched on to avoid tabs as required by the Fortran
standards unless the user has set fortran_have_tabs in .vimrc.'textwidth' is set to 72 for fixed source format as required by the
Fortran standards and to 80 for free source format.'formatoptions' is set to break code and comment lines and to preserve long
lines. You can format comments with gq.
For further discussion of fortran_have_tabs and the method used for the
detection of source format see ft-fortran-syntax.

Options:'modeline' is switched off to avoid the danger of trojan horses, and to
avoid that a Subject line with "Vim:" in it will cause an
error message.'textwidth' is set to 72. This is often recommended for e-mail.'formatoptions' is set to break text lines and to repeat the comment leader
in new lines, so that a leading ">" for quotes is repeated.
You can also format quoted text with gq.

Local mappings:<LocalLeader>q or \\MailQuote
Quotes the text selected in Visual mode, or from the cursor position
to the end of the file in Normal mode. This means "> " is inserted in
each line.

Two maps, <C-]> and <C-T>, are provided to simulate a tag stack for navigating
the PDF. The following are treated as tags:

- The byte offset after "startxref" to the xref table
- The byte offset after the /Prev key in the trailer to an earlier xref table
- A line of the form "0123456789 00000 n" in the xref table
- An object reference like "1 0 R" anywhere in the PDF

then this determined the file type: plaintex (for plain TeX), context (for
ConTeXt), or tex (for LaTeX). Otherwise, the file is searched for keywords to
choose context or tex. If no keywords are found, it defaults to plaintex.
You can change the default by defining the variable g:tex_flavor to the format
(not the file type) you use most. Use one of these: